1. Field of the Invention
The present invention relates generally to injection molding and, more particularly, to a drop tip for injection molding.
2. Description of the Related Art
Injection molding is a widely known manufacturing process used to produce a variety of parts. Injection molding involves introducing a molten material, for example a molten plastic or resin, into a cavity within a mold until the cavity is filled. The molten material hardens in the mold in the shape of inner surfaces of the cavity. After the molten material hardens or cures, the hardened or cured material is removed from the cavity.
For injection molding, a manifold assembly is typically used for conveying molten material from a central injection portion or sprue to a number of cavities or to multiple points within one large cavity of the mold. An example of such a manifold assembly is disclosed in U.S. Pat. No. 4,964,795 to Tooman. In that patent, a manifold assembly has an integral or one piece, cast or steel, cylindrical or rectangular manifold with a passageway and at least one nozzle extending outwardly from the manifold and having a passageway through which a molten material may pass. The terminal end of the passageway of the nozzle, called a gate, is in fluid communication with the cavity of the mold. The nozzle may fluidly communicate with a drop tip attached thereto and passes through the mold or terminates in the mold. The drop tip has an internal bore that is generally straight or linear from its inlet to an outlet thereof.
It is also known that the manifold assembly may be used to mold colored plastic parts. Typically, the manifold assembly is used to mold the plastic part with a first color and then with a second color. However, the internal bore of the drop tip retains a portion of the first color prior to molding the second color. During the injection molding process, the first few parts molded will have a mix of the first color and the second color, resulting in scrap parts.
Therefore, it is desirable to provide a drop tip that has an internal bore that reduces or eliminates the retention of plastic material. It is also desirable to provide a drop tip for molding multiple colored parts that eliminates mixing of the colors during the molding process. It is further desirable to provide a drop tip for molding colored plastic parts that minimizes or eliminates scrap due to a change of colors as a result of the molding process. Therefore, there is a need in the art to provide a drop tip that meets these desires.